Question 16 What is the oxidation number of the chlorine atom in perchloric acid
ID: 543147 • Letter: Q
Question
Question 16 What is the oxidation number of the chlorine atom in perchloric acid, HCIO4? No right choice. Question 17 What type of chemical reaction releases energy into the surroundings? Exothermic Endothermic No right choice. Pyrolysis Question 18 Which of the following makes it possible for autoignition to take place? The reactants and products have reached thermal equilibrium. The temperature is hot enough that reactant molecules have already absorbed more energy than the activation energy for the reaction No right choice. There is an excess of fuel present at room temperature Question 19 If the specific heat of a metal is 0.659 JIg C, what mass of abject l absorb 3500J of energy to increase its temperature from 22°C to 232°C? 0.0395 g 11.0 g 25.3 g No right choice. Question 20 What is the heat of combustion of gasolineif 4.00 g of gasoline are burned in a calorimeter to raise the temperature of 500.0 mL of water from 10.2 C to 94.2"C? Recall that the specific heat capacity of water is 4.184 4.40 x 104 J,g No right choice. 2.51 x 103J/g -4.40 × 104 J/gExplanation / Answer
16) 1 * (oxidation state of H) + 1 * (oxidation state of Cl)
+ 4 * (oxidation state of Oxygen ) = 0
1 * 1 + 1 * (oxidation state of Cl) + 4 * ( - 2) = 0
- 8 + 1 + Oxidation state of Cl = 0
Oxidation state of Cl = +7
So, option 1 is the correct choice.
17) exothermic reaction release energy into surrounding where as endothermic reaction absorb heat from surrounding, and pyrolysis is also a kind of endothermic reaction.
So, option 1 is the correct choice.
18) excess of fuel at room temperature can cause autoignition to take take place.
Option 4 is the correct choice.
19) since Q = m c T
3500 J = m * (0.659 J / g °C) (232 °C - 22 °C)
m = 3500 J / (0.659 J / g °C) (210 ° C)
m = 25.3 g
Option 3 is the correct choice.